流動法によるPb-FeO_<1.5>-CaO-SiO_2系およびPbO-ZnO-FeO_2系スラグ融体中のPbOの蒸気圧測定

概要

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To obtain the vapor pressure data of PbO in the PbO base slags with the high content of PbO, a transpiration method using a vertical volatilization chamber was developed and the vapor pressures were determined at 1, 423 and 1, 473 K for liquid PbO-FeO1.5-CaO-SiO2 and PbO-ZnO-FeO1.5-CaO-SiO2 slags nearly corresponding to those in the oxidation zone of the QSL lead smelting furnace. For any slag investigated, the activity of PbO was found to present a negative deviation from the Raoultian behavior and the activity coefficient of PbO showed a minimum value at the mole fraction of PbO in the slag with about 0.5. It was found that the acitivity coefficient of PbO increased with increasing Q of the slag, defined by Q = mass % CaO/(mass % SiO2 + mass % CaO). It was also clarified that the activity coefficient of PbO in the slag with ZnO was smaller than that in the slag without ZnO. The observed behaviors were explained qualitatively on the basis of the chemical affinity between PbO and other components in the slag. The partial pressures of various lead components in the gas phase were evaluated using the obtained thermodynamic data and it was suggested that the elemental lead species was predominant in the gas phase corresponding to the oxidation zone of the QSL furnace where the metallic lead phase coexists with the slag phase.
社団法人資源・素材学会の論文
1999-11-25